Enclosure for deep bass.

[Buck 5,000+ posts]

ported. end of discussion

 

[BEAVER.989 10+ year member]

I'm not doing the ported. Im actually doing the sealed, and my current drawing has it all the way to one side for better in vehicle location. However, it seems that on the rear of the cone (the part exposed to the inside of the box), the side that is close to the side of the box will not recieve as much reflected wave energy as the side that is more open to the bulk of the enclosure.

If that were a valid concern home audio speakers would place the woofer in the center of the cabinet instead of the very bottom...

I think you're overthinking things, man... nothing wrong with that, though. I am much the same.

 

[SubsonicSounds 10+ year member]

If that were a valid concern home audio speakers would place the woofer in the center of the cabinet instead of the very bottom...
I think you're overthinking things, man... nothing wrong with that, though. I am much the same.

Thought the EXACT same thing, but once again began thinking about it, and I believe that most of the "tower" type home enclosures that you are speaking of are chambered, which would creat a small enclosure at the bottom where the speaker would actually be centered.

 

[BEAVER.989 10+ year member]

some are chambered, some are not. you have nothing to worry about.

 

[SubsonicSounds 10+ year member]

ported. end of discussion

Oh, man. Thanks. I think im just going to go back to bed and sleep knowing that my problems are all so simply solved. And to think guys, all this could have ended with 4 words. LOL.

If you read above, someone suggested that. But I think most would agree that it was certainly not the end of the discussion.

To be fair...

I do know that a vented enclosure will be the optimum type for this ASSUMING a relatively ideal enclosure design, but I think we have established that creating a relatively ideal vented design for my tastes would be very time consuming, and would take up a great deal of space to house the required length tubes for my tuning frequencies without creating wave distortion through the compression/decompression process.

 

[BEAVER.989 10+ year member]

I'm not going to try to twist your arm, but I really believe the ported solution is best, as well.

If it's just the matter of designing the enclosure that's holding you back, speak up. I'll be more than happy to model up a design for you in WinISD, if you'd like.

Ultimately, it's your decision, though. If you're more comfortable with a sealed design, then stick with it. I wish you luck in whatever you decide to do.

 

[SubsonicSounds 10+ year member]

some are chambered, some are not. you have nothing to worry about.

I can speculate that the air pressure effects that I am worried about could be negligible considering the overall internal volume of the enclosure. I can see how the situation that i am worried about would be no different than the effects of speaker location relative to panels of the cars interior in some cases with trunk mounted subwoofers.

You might be right. Thank you for the insight.//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[SubsonicSounds 10+ year member]

I'm not going to try to twist your arm, but I really believe the ported solution is best, as well.
If it's just the matter of designing the enclosure that's holding you back, speak up. I'll be more than happy to model up a design for you in WinISD, if you'd like.

Ultimately, it's your decision, though. If you're more comfortable with a sealed design, then stick with it. I wish you luck in whatever you decide to do.

I may actually ask you for some help in the near future. I do need to finish this project first. The good news is if I eventaully design a vented enclosure (leaning towards T-Line), I have a 10 inch type-e as well that can be used in whatever box I do not decide to keep. Just throw that in the closed and connect it to a home amp.

 

[NissanKicker 10+ year member]

Why don't you just cut into your reak deck ( Like an IB setup )... And seal off the trunk.

... Kind of like how Lexus does their rear stage ( 10" sub in rear deck only ).

 

[miker 5,000+ posts]

How about, you make a sealed AND ported box..

Now thats an idea..

 

[SubsonicSounds 10+ year member]

Why don't you just cut into your reak deck ( Like an IB setup )... And seal off the trunk. ... Kind of like how Lexus does their rear stage ( 10" sub in rear deck only ).

Actually, that would be a good possibility with potentially superior results. This way of baffling the sub would provide an enourmous amount of effective box volume behind the cone. I would without a doubt be losing a significant amount of power handling, as the air reflex effect would be very low, allowing for more unrestricted cone movement, eventually reaching the limits of excursion. I will have to see how my sub performs in the box that I designed (should have it by Friday), to see how much of a factor the electromechanical limits of the suwoofer design will be.

The rear stage infinite baffle design has two inherent advantages that immediately come to mind.

1. The sound waves are reflecting directy from the rear window towards the front of the car, possibly producing low frequencies with better sound imaging for the front seat listener.

2. The air pressure restrictions behind the cone will be very limited, which could be advantageous for low frequency propogation in the way mentioned above.

Ever heard a well amplified pair of 6x9's mounted in the stock location? Some can hit pretty low!

Disadvantage:

However, in my current plans, with the sub front face playing into the trunk, with one seat down, I am effectively using the trunk as a source of interior gain.

Nonetheless....

Good call Nissan. Btw, since you seem to know about some specific applications of IB subs in factory installations, don't be afraid to post links! Don't think for a minute that I wont read them.

 

[SubsonicSounds 10+ year member]

How about, you make a sealed AND ported box..
Now thats an idea..

Do you mean utilizing sealed and ported technology at the same time in some type of bandpass, or do you mean actually making two seperate boxes? I have metioned experimenting with both types of enclosure and probably will.

 

[miker 5,000+ posts]

Do you mean utilizing sealed and ported technology at the same time in some type of bandpass, or do you mean actually making two seperate boxes? I have metioned experimenting with both types of enclosure and probably will.

I mean experimenting with both kinds,

Sorry I just read the first page and part of the last, and that was all I could think, since it's not even a large enclosure trying a couple boxes won't take too much time or cost too much.

 

[SubsonicSounds 10+ year member]

I agree, and as I said, I still can utilize both boxes regardless of the outcome.

 

[helotaxi 5,000+ posts]

***New Question*** In a rectangular enclosure, is there a problem mounting the driver closer to one end of the enclosure, or does it need to be centered to eliminate uneven pressure on the back of the speaker? In other words, will I cause unwanted damage or distortion by having the speaker close to one end of the enclosure?

At sub bass frequencies, there are no "inbox reflections" or anything of that sort to worry about. There are no "waves" inside the box at all. The frequencies in question have a 20+ ft wavelength. The air inside the box simply pressurizes as a whole and rarifies as a whole as the cone moves. You're thinking WAY to much about this and assuming that concerns exist where ther are none.

You could build an extremely low tuned ported enclsure and accomplish whatyou want but it will have 2 characteristics that will be detrimental to your goal. First it will have to be HUGE. Second the port will have to be HUGE making the gross size of the box that much bigger. To be playing the freqs that you're looking for, you're looking at a tuning of 20hz, probably lower. Power handling will not be any better than with a large sealed box because the enclosure would have to be very large to keep the output around tuning from being suppressed below what you would get from a large sealed enclosure at that frequency. Yes, that's what happens when you put a sub in a ported enclosure tuned much lower than it wants to be tuned, output actually drops (which kinda defeats the purpose to going ported in the first place). You have to make the box HUGE to boost that low output shelf back to somewhat normal levels. You can't get around Hoffman's Iron Law, even with a ported enclosure. You can have efficiency, low frequency extension and a small box, pick two.